Hi Alex, Paul, VLF,
I found that the fascination risis with the square of the wavelength!
My congrats again to your ufb VLF RX and thank you for your effeorts. We
are very successful.
I never expected that we can transfer messages on 5170 Hz over that path
with such a rate. Now we have some important data: We can expect 6 dB in
23 uHz during an average quiet night. So now we can calculate how many
days must be expected for a longer message, like we did on 6470 Hz. I
would like to try a 12 character message soon. It takes just 2 weeks or
so :-)
Paul, maybe you are interested in wav files for reprocessing. I attached
the 23th and 20th...24th(weighted). The size is very small...
For the 23th i got an even better result with a time offset of 1754 seconds.
My ERP on 5170 Hz is 2 dB lower than on 6470 Hz. But the SNR we observe
seems not to differ much from that on 6470 Hz. The opposite of what all
the curves predict!!!!!!
So what will happen arround 4 kHz???!!! Will we be able to send messages
over that respectable distance? I bet!
From 4 kHz it is not so far until we reach 2.97 kHz!! That's my dream
for this season, 2 characters on 2.97 kHz over that path!
We were focused on that one graph showing VLF propagation as a function
of the frequency, for different distances (and constant ERP!). But the y
axis shows field strength and not SNR! What is when most of the noise
comes from far away (> 4000 km), which is the case in winter on our
path!? Then the noise will drop stronger than the signal? This first
experiment seems to be a first sign for that assumption. So what happens
on 4.47 kHz relative to 5.17 kHz? The ERP will drop by just 1.2 dB. But
the noise may fall much stronger!! We will check that too :-) And on
2.97 kHz, relative to 5.17 kHz: Just 5 dB less ERP and maybe a much
better noise reduction!
73, Stefan
Am 25.10.2017 18:23, schrieb Alex K:
Hello VLF, Stefan
I'm glad to report about sucsessfull decode of 1-char ebnaut message
sended on 5170.1 Hz 20,22,23 and 24 October.
Message was decoded by weighted stacking, unweighted stacking and from
23 okt file only. Other files give very poor decode with many false
decodes or only false decodes.
In attacment we can see best decode from weighted stacking.
Also all ebnaut-files is available here: http://rn3aus.narod.ru/5170.zip
My VY congratulations to Stefan! Ab
ebnaut-rx V0.7a
input file sum.wav
sample rate 0.342935 per second
rx frequency 5170.1
file start time 2017-10-24 15:30:58.390
polynomial 8K19A
crc size 6
number of chars 1
block size 12
symbol period 180.000
number of symbols 240
list length 20
start offset 1754.000
freq offset 0.000000
cores 1
skipped 1755.434703 seconds to start
initial reference phase -27.5
---------------------------------------------
found =
list rank 0
reference phase 0 0 0 0
carrier S/N 12.10 dB in 23.1 uHz, -34.26 dB in 1Hz, -68.24 dB in 2.5kHz
carrier Es/N0 -11.70 dB
carrier Eb/N0 4.54 dB
info bit period 7578.95 seconds
symbol error rate 79/240 = 32.917 %
Es/N0 from symbol errors -10.0 dB
Eb/N0 from symbol errors 6.2 dB
Shannon capacity 1.9 bits/hour
Shannon efficiency 25.2 %
symbols file sum-symbols.csv
elapsed 2 seconds
23.wav
Description: Wave audio
sum_20-24.wav
Description: Wave audio
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